1. Field of the Invention
The present invention relates to a method of allocating an internet protocol address, and more particularly, to a method of allocating an internet address in a broadband wireless access system.
2. Discussion of the Related Art
A structure of a network that supports a mobile internet protocol (IP) includes, inter alia, a Home Agent (HA), a Foreign Agent (FA), and a mobile station (MS). For operation of the mobile IP, processes such as agent discovery, registration, and routing are necessary.
In detail, the agent discovery process determines whether the MS is currently connected to the home network or whether the MS is located in a foreign network. If the MS has moved to a different or foreign network, new (now current) location information is sent to the HA during the registration process so that the MS can continue. to receive the same service received at the home network. When the MS is registered to a foreign network, the routing process is used to route datagram transmitted or received by the MS.
There are two methods available in the mobile IP in determining Care of Address (CoA) when the MS has moved to a different subnet. A FA-CoA is provided by the FA via an Agent Advertisement message, and the IP address of the FA is used as the CoA. A co-located CoA is a scheme by which the MS receives the CoA via a Dynamic Host Configuration Protocol (DHCP) located in the foreign network.
According to the conventional art, when the MS performs handover with a BS of an Access Service Network (ASN) which belongs to another subnet, the MS has to re-establish the IP address in order for the MS to continue to receive the IP service. If the MS is using a service sensitive to delay, such as Voice over Internet Protocol (VoIP), there is delay from the DHCP server address allocation procedure to registering with a new CoA for re-establishing the IP address. This type of delay decreases quality of real time traffic and capability of data communication.